标题： 从湍流测量中准确估计三阶矩 显示英文标题

标题： Accurate estimation of third-order moments from turbulence measurements

摘要： 波里塔诺和普凯特定律是科姆洛夫的四分之五定律在不可压缩MHD中的推广，它使得通过三阶矩来测量不可压缩MHD湍流的能量级串率成为可能。 在水动力学中，由于速度差的概率分布几乎是对称的且三阶矩相对较小，因此准确测量三阶矩需要大量的数据。 最近首次对太阳风湍流中的能量级串率进行了测量，但没有仔细考虑所需三阶矩的准确性和统计不确定性。 本文研究了作为样本大小N函数的三阶矩的统计收敛性。结果表明三阶矩的准确性取决于数据集跨越的相关长度数，并且开发了一种估计三阶矩统计不确定性的方法。 该技术使用风洞数据和太阳风数据进行说明。 显示英文摘要

摘要： Politano and Pouquet's law, a generalization of Kolmogorov's four-fifths law to incompressible MHD, makes it possible to measure the energy cascade rate in incompressible MHD turbulence by means of third-order moments. In hydrodynamics, accurate measurement of third-order moments requires large amounts of data because the probability distributions of velocity-differences are nearly symmetric and the third-order moments are relatively small. Measurements of the energy cascade rate in solar wind turbulence have recently been performed for the first time, but without careful consideration of the accuracy or statistical uncertainty of the required third-order moments. This paper investigates the statistical convergence of third-order moments as a function of the sample size N. It is shown that the accuracy of the third-moment depends on the number of correlation lengths spanned by the data set and a method of estimating the statistical uncertainty of the third-moment is developed. The technique is illustrated using both wind tunnel data and solar wind data.